The present invention relates to a .beta.-lactam compound having a hydroxyethyl group at the C3-position where the hydroxyl group is protected and having a silylether group at the C4-position, and a process for preparing the compound.
Since the .beta.-lactam compound of the present invention has a highly reactive silylether group, it is a useful intermediate which can be converted into various derivatives. For instance, 3-(1-hydroxyethyl)-4-acetoxyazetidin-2-on and 3-(1-hydroxyethyl)-4-haloazetidin-2-one, which are both useful for preparing thienamycin known as a .beta.-lactam antibiotics of the fourth generation, can be obtained by substitution reaction of the silylether group at the C4-position of the compound of the present invention.
There hitherto has been unknown the .beta.-lactam compound with a silylether group at the C4-postion. Also, there has been unknown a process for preparing the .beta.-lactam compound having an O-protected hydroxyethyl group at the C3-position and a silylether group at the C4-position.
As a result of continuous efforts of the inventors, it has been found that the above .beta.-lactam compound can be a useful intermediate for preparing carbapenem .beta.-lactam compound and the desired .beta.-lactam ring could be formed by a reaction of an enolsilylether and chlorosulfonylisocyanate. Thus, the present invention has been accomplished.